While substantial effort and attention continues toward the development of newer and more sustainable energy supplies, the conservation of energy by increased energy efficiency remains crucial to the world's energy future. Along with improvements in the physical plant associated with home heating and cooling, including improvements in insulation, higher efficiency furnaces, and in other such improvements, substantial increases in energy efficiency can be achieved by better control and regulation of home heating and cooling equipment. By efficiently controlling operation of heating, ventilation, and air conditioning (HVAC) equipment, substantial energy can be saved.
Many currently available HVAC thermostatic control systems can be characterized as belonging to one of two categories: (1) a first category that includes many simple, non-programmable home thermostats, each typically consisting of a single mechanical or electrical dial for setting a desired temperature and a single HEAT-FAN-OFF-AC switch; and (2) a second category that includes many programmable thermostats, which have become more prevalent in recent years and which feature many different HVAC-system settings that can be individually manipulated. While being easy to use for even the most unsophisticated occupant, thermostats of the first category are performed manually by the user. As a result, substantial energy-saving opportunities are often missed for all but the most vigilant users. Moreover, advanced energy-saving settings are not generally provided, including an ability to specify a custom temperature swing, the difference between the desired set temperature and actual current temperature that triggers activation of the heating/cooling unit. Users of thermostats of the second category are often intimidated by a large number of switches and controls, and therefore seldom adjust the manufacturer defaults to optimize their own energy usage despite the fact that these thermostats are capable of operating HVAC equipment with energy-saving profiles. Indeed, in an unfortunately large number of cases, a home user may permanently operate the unit in a “temporary” or “hold” mode, manually manipulating the displayed set temperature as if the unit were a thermostat of the first category.